smbc.co.jp Domain Breach Exposure Report

The domain smbc.co.jp has experienced a significant number of data breaches and infostealer events, totaling over 32,000 incidents between July 2025 and June 2026. The majority of these events are categorized as historical data breaches (73.4%), with active infostealer logs making up the remainder (26.6%). A notable surge in employee-related events occurred in January 2026, with 281 incidents, followed by smaller spikes in March, April, and May. The most prevalent malware families associated with these events are LummaC2 (32.8%), Vidar (6.4%), and Rhadamanthys (4.7%), all of which are known for credential theft. The high volume of data breaches and infostealer activity, coupled with the prevalence of credential-stealing malware, indicates a severe exposure risk. The targeted services include smbc.co.jp's direct banking portals, suggesting potential compromise of financial transaction data or customer credentials. The majority of the data breach events originate from "Combolist sources," which are often derived from previous large-scale credential stuffing attacks. Remediation should focus on strengthening authentication mechanisms, enhancing endpoint security to detect and prevent infostealer malware, and conducting thorough investigations into the identified data breaches to understand the scope of compromised information and affected individuals.